The preposition "pour" is used to indicate the action of transferring a liquid from one container to another. It often describes the act of causing a liquid to flow out, typically from a bottle, jug, or similar vessel. For example, you might pour water from a pitcher into a glass. In addition to its literal meaning, "pour" can also be used in a figurative sense. For instance, one might say they are pouring their heart out, which means expressing emotions deeply. This usage highlights the idea of sharing or releasing something, similar to how liquid is poured out.